A poured molten metal quantity control device ordinarily includes a fixed plate, which has a pouring port and is composed of a refractory detachably mounted on a base plate fixed to a ladle and the like, and a slide plate, which has a pouring port and is composed of a refractory detachably mounted on a slide frame, and controls the pouring feed rate of the molten metal by adjusting the degree of opening between the pouring port of the fixed plate and the pouring port of the slide plate by a slide system for linearly sliding the slide plate along the base plate.
A metal slide system and a roller slide system are available as the slide system of the slide frame in the poured molten metal quantity control device employing the linear slide system, and the basic structure of the metal slide system is widely known and used from the beginning of development of this type of apparatuses to the present (refer to, for example, Japanese Patent Publication Nos.1-38592 and 48-4697 (U.S.Pat. Nos. 4,848,604 and 730870).
In the metal slide system, since a slide plate is pressed against a fixed plate through a slide frame by a hydraulic cylinder and the like to thereby linearly move the slide plate, the metal slide system is advantageous in that the positions at which the degree of opening of a pouring port is completely opened or closed can be obtained with relatively high accuracy.
However, to slide the slide frame to adjust the degree of opening of the pouring port, there is required drive force larger than the sum of the friction force generated on the slide surface between the fixed plate and the slide plate and the friction force generated on the slide surface between the slide frame and a guide member thereof.
Further, since the slide frame and the guide member thereof are worn, they must be replaced, for example, about every 500 heats. Accordingly, maintenance cost such as a disassembly and adjustment cost, parts cost, and the like increases, and further a troublesome job is required to apply a lubricant onto the slide surface between the fixed plate and the slide plate and onto the slide surface between the slide frame and the guide member.
The roller slide system is developed to overcome the problem of friction force in the metal slide system described above (refer to, for example, Japanese Patent Publication No. 62-58816 (U.S. Pat. No. 4,728,014). The roller slide system can reduce the friction force generated at the time when a slide plate is slid, by using a roller, and further can reduce apparatus cost and maintenance cost. However, since the point of action of the roller to the periphery of a pouring port of the slide plate shifts and thus press force exerted to the periphery of the pouring port lacks balance, from which a possibility arises in that the press force is reduced on the periphery of the pouring port.
In contrast to these linear slide type poured molten metal quantity control devices, there is available a rotary type poured molten metal quantity control device which relatively changes respective pouring ports from a completely open position to a completely close position by slidingly turning a slide plate brick with respect to a fixed plate brick. The rotary type poured molten metal quantity control device is advantageous in that it is comparatively compact because a worm device and the like are used as a means for turning a slide plate brick in contrast that the linear slide type poured molten metal quantity control device requires an additional expansion length corresponding to the stroke of the slide plate, press force is exerted in relatively good balance, the maintenance of device is easy, and total cost can be reduced because of the extended life of a refractory. Thus, many small to large rotary type poured molten metal quantity control devices are used as poured molten metal quantity control devices (refer to Japanese Patent Publication No. 5-200533).
FIG. 9 is a view showing an example of a conventional rotary type poured molten metal quantity control device that controls a pouring feed rate by controlling the degrees of opening of a pouring port of a fixed plate brick 20 and a pouring port of a slide plate brick 50 from a completely open position to a completely close position by the sliding turn angle of the slide plate brick 50 that slidingly turns in contact with the fixed plate brick 20. The turning operation is executed by a worm 90 and a worm gear 91 coupled with a frame 70 for supporting the slide plate brick 50.
However, when the slide plate brick 50 is turned to the completely open/close positions of the pouring ports by an electric motor or a hydraulic motor through the worm gear 91, a worker must stop the slide plate brick 50 at the completely open/close positions by observing marks or by detecting the positions of the pouring ports by a turn angle sensor. Accordingly, more prudence is required to the workability for controlling the pouring feed rate, and a manipulation is somewhat troublesome and takes a long time.
FIG. 10 is a view showing an example of a conventional linear slide type poured molten metal quantity control device. The conventional poured molten metal quantity control device controls a pouring feed rate by controlling the degrees of opening of a pouring port of a fixed plate brick 200 and a pouring port of a slide plate brick 500 from a completely open position to a completely close position by the slide amount of the slide plate brick 500 that linearly slides in contact with the fixed plate brick 200 fixed to a base plate 100. The sliding operation is executed by a rod stroke of a hydraulic cylinder 900. The linear slide type poured molten metal quantity control device is advantageous in that since operation start and end positions can be firmly determined by the rod stroke, a control can be securely carried out by matching the completely open/close positions of the pouring ports to the operation start and end positions.
However, in a conventional door type poured molten metal quantity control device, in which a fixed plate brick or a slide plate brick is replaced or used after it is reversed as a countermeasure executed in an actual job to against bricks worn in the vicinities of pouring ports, when a door is opened and closed, a door side must be disconnected from a drive side by any means. That is, in FIG. 10, a coupling portion 910 between the hydraulic cylinder 900 and a support portion 700 of the slide plate brick 500 must be made in a separable type, and a trouble job for separating the coupling portion 910 must be executed each time the brick is reversed. As long as the conventional door type is employed, this job is indispensable in any of the slide system and the rotary system.
Patent Document 1: Japanese Examined Patent Application
    Publication No. 1-38592 (column 3, lines 1-26, FIG. 2)    Patent Document 2: Japanese Examined Patent Application    Publication No. 48-4697 (column 2, lines 21-30, FIG. 2)    Patent Document 3: Japanese Examined Patent Application    Publication No. 62-58816 (column 3, lines 1-26, FIG. 2)    Patent Document 4: Japanese Unexamined Patent Application    Publication No. 5-200533 (column 3, lines 22-34, FIG. 1)